The coronavirus hooks onto ACE-2 receptors, known as the “gateway” into cells inside the body. These receptors are found in the respiratory tract and the lungs, which is where the virus initially enters cells, as well as other organs.
A team of researchers led by Johns Hopkins University School of Medicine have now found the eyes create ACE-2, making them a target for the virus.
It means if droplets from an infected person’s sneeze or cough were to reach the tissue of the eye, the virus could begin infiltrating cells there.
This may be the reason why, in some cases, the patient has developed conjunctivitis – an inflammation of the eye which causes it to become red and infected.
Tears may also help spread the infection, scientists said.
The team was led by Lingli Zhou of the Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore.
They examined ten human post-mortem eyes from people who did not die of COVID-19 for the expression of ACE2 (angiotensin-converting enzyme 2).
ACE-2 is believed to be the point of access for the pathogen. Its spiky surface latches onto the receptors and, from there, infects the cell and duplicates.
Dr Zhou and colleagues wrote: “Together, these results indicate that ocular surface cells including conjunctiva are susceptible to infection by SARS-CoV-2, and could therefore serve as a portal of entry as well as a reservoir for person-to-person transmission of this virus.”
The investigation was inspired by “extensive speculation” that eye tissue is a potential site of virus entry.
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Just 26 people have died in the disease in China when doctor Wang Guangfa said he believed he had been infected with the SARS-like virus because he was not wearing protective goggles.
Several days before experiencing pneumonia, Dr Wang – a Peking University respiratory specialist – observed his eyes were red.
Paul Kellam, professor of virus genomics at Imperial College London, told MailOnline at the time it was “absolutely possible”.
“If you have droplets sneezed at you, they will wash from your eye to your nose,” he told MailOnline.